def main():

    X = int(input())
    if X >=30: return "Yes"
    return "No"

if __name__ == '__main__':
    print(main()) def main():

    X = int(input())
    if X >=30: return "Yes"
    return "No" main X = int(input()) X int(input()) int input() input if X >=30: return "Yes"
     X >=30 X 30 return "No" "No" if __name__ == '__main__':
    print(main()) __name__ == '__main__' __name__ '__main__' print(main()) print main() main def main():

    X = int(input())
    if X >=30: return "Yes"
    return "No" def main():

    X = int(input())
    if X >=30: return "Yes"
    return "No" main
def main():

    X = int(input())
    if X >=30: return "Yes"
    return "No"

if __name__ == '__main__':
    print(main())
